Many configurations of engine cylinder intake ports, or cylinder head inlet ports and the like, have been designed and/or utilized to create rotation or swirl of intake charges supplied to the combustion chamber or cylinder. In general however, intake port, or passage, configurations which have been effective in creating significant charge swirl have also resulted in reducing the mass of charge flowing into each cylinder on its intake stroke so as to result in what is called reduced volumetric efficiency. This implies a reduction in the charge volume when calculated at standard temperature and pressure.
In view of a renewed interest among engine designers in recent years in utilizing increasing amounts of charge swirl in spark ignited internal combustion engines, such as gasoline engines, a large number of proposals for swirl producing intake ports have been made. These have included both fixed geometry intake ports and variable geometry ports which have incorporated one or more movable components intended to provide a high degree of swirl under low engine load conditions and a reduced degree of swirl with improved charging and volumetric efficiency under high load conditions where a maximum cylinder charge is desired. However, a need remains for a simple fixed geometry intake port which can provide a substantial degree of swirl together with high volumetric charging efficiency.